<template>
  <div class="slider" ref="slider">
    <div class="slider-group" ref="sliderGroup">
      <slot></slot>
    </div>
    <div class="dots">
      <span class="dot" v-for="(dot,index) in dots" :class="{'active':index==currentIndex}"></span>
    </div>
  </div>
</template>

<script>
  import {addClass} from 'common/js/dom';
  import BScroll from 'better-scroll';
  export default {
    name: 'slider',
    props: {
      loop: {type: Boolean, default: true},
      autoPlay: {type: Boolean, default: true},
      interval: {type: Number, default: 3000}
    },
    data () {
      return {
        dots: [],
        currentIndex: 0
      };
    },
    methods: {
      _setSliderWidth (isReize) {
        this.children = this.$refs.sliderGroup.children;
        let totalWidth = 0;
        let width = this.$refs.slider.clientWidth;
        let l = this.children.length;
        for (let i = 0; i < l; i++) {
          let child = this.children[i];
          addClass(child, 'slider-item');
          child.style.width = width + 'px';
          totalWidth += width;
        }
        if (this.loop && !isReize) {
          totalWidth += (width * 2);
        }
        this.$refs.sliderGroup.style.width = totalWidth + 'px';
      },
      _initSlider () {
        this.slider = new BScroll(this.$refs.slider, {
          scrollX: true,
          scrollY: false,
          momentum: false,
          snap: true,
          snapLoop: this.loop,
          snapThreshold: 0.3,
          snapSpeed: 300
        });
        this.slider.on('scrollEnd', () => {
          let pageIndex = this.slider.getCurrentPage().pageX;
          if (this.loop) {
            pageIndex -= 1;
          }
          this.currentIndex = pageIndex;
          if (this.autoPlay) {
            this._play();
          }
        });
        this.slider.on('beforeScrollStart', () => {
          if (this.autoPlay) {
            clearTimeout(this.timer);
          }
        });
      },
      _initDots () {
        let l = this.children.length;
        if (this.loop) {
          l -= 2;
        }
        this.dots = new Array(l);
      },
      _play () {
        let pageIndex = this.currentIndex + 1;
        if (this.loop) {
          pageIndex += 1;
        }
        this.timer = setTimeout(() => {
          this.slider.goToPage(pageIndex, 0, 300);
        }, this.interval);
      }
    },
    mounted () {
      setTimeout(() => {
        this._setSliderWidth();
        this._initSlider();
        this._initDots();
        if (this.autoPlay) {
          this._play();
        }
      }, 20);
      window.addEventListener('resize', () => {
        if (!this.slider) {
          return;
        }
        this._setSliderWidth();
        this.slider.refresh();
      });
    },
    activated () {
//      console.log(`actived`);
      if (this.autoPlay) {
        this._play();
      }
    },
    deactivated () {
//      console.log(`deactivated`);
      clearTimeout(this.timer);
    },
    beforeDestroy () {
      clearTimeout(this.timer);
    }
  };
</script>

<style lang="less" scoped="">
  @import '~common/css/variable.less';

  .slider {
    min-height: 1px;
    .slider-group {
      position: relative;
      white-space: nowrap;
      overflow: hidden;
      width: 100%;
      .slider-item {
        float: left;
        box-sizing: border-box;
        overflow: hidden;
        text-align: center;
      }
      a {
        display: block;
        width: 100%;
        overflow: hidden;
        text-decoration: none;
      }
      img {
        display: block;
        width: 100%;
      }
    }
    .dots {
      position: absolute;
      right: 0;
      left: 0;
      bottom: 12px;
      text-align: center;
      font-size: 0;
      .dot {
        display: inline-block;
        margin: 0 4px;
        width: 8px;
        height: 8px;
        border-radius: 50%;
        background: @color-text-l;
        &.active {
          width: 20px;
          border-radius: 5px;
          background: @color-text-ll;
        }
      }
    }
  }
</style>
